# Trie（发音类似 "try"）或者说 前缀树 是一种树形数据结构，用于高效地存储和检索字符串数据集中的键。这一数据结构有相当多的应用情景，例如自动补完和拼
# 写检查。 
# 
#  请你实现 Trie 类： 
# 
#  
#  Trie() 初始化前缀树对象。 
#  void insert(String word) 向前缀树中插入字符串 word 。 
#  boolean search(String word) 如果字符串 word 在前缀树中，返回 true（即，在检索之前已经插入）；否则，返回 false
#  。 
#  boolean startsWith(String prefix) 如果之前已经插入的字符串 word 的前缀之一为 prefix ，返回 true ；否
# 则，返回 false 。 
#  
# 
#  
# 
#  示例： 
# 
#  
# 输入
# ["Trie", "insert", "search", "search", "startsWith", "insert", "search"]
# [[], ["apple"], ["apple"], ["app"], ["app"], ["app"], ["app"]]
# 输出
# [null, null, true, false, true, null, true]
# 
# 解释
# Trie trie = new Trie();
# trie.insert("apple");
# trie.search("apple");   // 返回 True
# trie.search("app");     // 返回 False
# trie.startsWith("app"); // 返回 True
# trie.insert("app");
# trie.search("app");     // 返回 True
#  
# 
#  
# 
#  提示： 
# 
#  
#  1 <= word.length, prefix.length <= 2000 
#  word 和 prefix 仅由小写英文字母组成 
#  insert、search 和 startsWith 调用次数 总计 不超过 3 * 104 次 
#  
#  Related Topics 设计 字典树 哈希表 字符串 
#  👍 912 👎 0


from typing import List


# leetcode submit region begin(Prohibit modification and deletion)
class Trie:

    def __init__(self):
        self.children = [None] * 26
        self.end = False

    def insert(self, word: str) -> None:
        node = self
        for ch in word:
            index = ord(ch) - ord('a')
            if node.children[index] is None:
                node.children[index] = Trie()
            node = node.children[index]
        node.end = True

    def searchPrefix(self, prefix: str) -> 'Trie':
        node = self
        for ch in prefix:
            index = ord(ch) - ord('a')
            if node.children[index] is None:
                return None
            node = node.children[index]
        return node

    def search(self, word: str) -> bool:
        node = self.searchPrefix(word)
        return node is not None and node.end

    def startsWith(self, prefix: str) -> bool:
        node = self.searchPrefix(prefix)
        return node is not None


# Your Trie object will be instantiated and called as such:
# obj = Trie()
# obj.insert(word)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)
# leetcode submit region end(Prohibit modification and deletion)


def log(*args, **kwargs):
    print(*args, **kwargs)


# 自定义类型判断空, 使用is not None
# 前缀树是多叉树, 子结点为数组,长度26, 标识子节点有哪些字母, 节点占位表示存在的字母
# 结构: 1. 存在哪些子结点的数组 2. 字符串是否结束
# 插入: 节点存在, 处理下一个, 节点不存在, 新建对应位置的节点
# 前缀查找, 存在即为有前缀
# 查找, 前缀存在, 且节点为结束节点
# class Trie:
#
#     def __init__(self):
#         self.children = [None] * 26
#         self.end = False
#
#     def insert(self, word: str) -> None:
#         node = self
#         for ch in word:
#             index = ord(ch) - ord('a')
#             if node.children[index] is None:
#                 node.children[index] = Trie()
#             node = node.children[index]
#         node.end = True
#
#     def searchPrefix(self, prefix: str) -> 'Trie':
#         node = self
#         for ch in prefix:
#             index = ord(ch) - ord('a')
#             if node.children[index] is None:
#                 return None
#             node = node.children[index]
#         return node
#
#     def search(self, word: str) -> bool:
#         node = self.searchPrefix(word)
#         return node is not None and node.end
#
#     def startsWith(self, prefix: str) -> bool:
#         node = self.searchPrefix(prefix)
#         return node is not None


if __name__ == '__main__':
    s = Trie()
    s.insert('apple')
    assert s.search('apple')
    assert s.search('app') is False
    assert s.startsWith('app')
    s.insert('app')
    assert s.search('app')
